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then be prioritized for follow-up sequencing to characterize if VOCs are present [39, 40]. In summary, monitoring rates of target failure as part of routine testing can potentially be a useful signal that there may be changes in the variant distribution in a given population. A recent survey by the ECDC found that 16 European countries are now using S-gene target failure as a variant prescreening strategy, to identify variants from positive PCR- test results, which may then be sequenced to confirm their identity [41]. This should be more widely encouraged as part of routine lab practice. 3.3 Use of sequencing to manage future impact of variants on diagnostics The Δ69/70 mutation in the B.1.1.7 variant is not the only mutation to interfere with a diagnostic test, and other mutations have previously been detected in other genes which resulted in PCR target failure [42]. It is likely that as new variants and mutations continue to emerge, there will be additional impact on diagnostics.

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